The existing step stool includes front leg tubes, rear leg tubes, a top footplate and a latch device. The front leg tubes pivotally join the rear leg tubes. The front portion of the top footplate pivotally joins the front leg tubes. A rail is provided between the rear leg tubes. The latch device is disposed in the top footplate and joins the rail, the leg tubes and a footplate disposed between the two leg tubes for assembly and disassembly. The step stool is used as a special ladder for a user to work on positions high above ground, the top footplate requires a solid connection to the other parts of the step stool. One such prior art step stool is described in the published patent application CN2889017Y entitled “A Latch Structure of the Step Stool” on Apr. 18, 2007 in the Chinese patent database in which a latch structure of the step stool is described. The latch structure includes a hook pivot to a first hinge plate, the hook rotates around the pivot point, the hook is disposed with a channel for the entry of the tongue fixed in the second hinge plate. A spring is fixed in the hook. A lock hook joins the hook rotatably by a pivot element. One end of the lock hook joins the free end of the spring fixed in the hook. The lock hook is disposed with a hook groove holding the tongue of the second hinge plate.
The release steps of the latch includes: 1. Rotate the lock hook, making the lock hook far away from the tongue; 2. continue to rotate the hook, making the hook far away from the tongue; 3. then rotate the first hinge plate relative to the second hinge plate, making the front leg tubes and the rear leg tubes fold together. As can be seen from the above, the release includes several steps with complicated release, resulting in inconvenient use.